Dust removing apparatus for an article classifier



Feb. 22, 1966 BOYCE 3,236,376

DUST REMOVING APPARATUS FOR AN ARTICLE CLASSIFIER Filed June 19, 1965T'Il3 l INVENTOR JOHN BOYCE ATTORNEY United States Patent 6 3,236,376DUST REMOVING AYPARATUS FOR AN ARTICLE CLASSIFIER John Boyce, San Jose,Caliti, assignor to FMC Corporation, San Jose, Calili, acorporation ofDelaware Filed June 19, 1963, Ser. No. 289,086 11) Claims. (Cl.209-1116) This invention relates to a dust removin apparatus and moreparticularly a dust removing apparatus for a sorting machine having anoptical sorting system.

An object of this invention is to provide a new and improved dustremoving apparatus.

Another object of this invention is to provide a new and improved dustremoving apparatus particularly adapted for an optical classifying orsorting machine.

Another object of this invention is to provide a new and improved dustremoving apparatus for an optical classifying machine which utilizes astream of gaseous fluid to entrain dust or any other foreign particleswhich may interfere with the optical classifying system of the machine.

The classifying or sorting apparatus to which this invention pertains isadapted to determine the basic color of objects such as rice, beans,peas and the like and on the basis of such color determination thearticles are classified. The machine is so constructed as to allowgravitational downward cascading movement of the articles. During suchcascading movement through various parts of the apparatus, the articlesgenerate a certain amount of dust due to the friction therebetween andthe friction with the walls of the machine. The dust so generated is inpart deposited upon certain of the optical elements of the classifyingsystem, thereby affecting the intensity of light utilized by the opticalsystem for classifying the articles and thus reducing the sensitivity ofthe system. As a result of this condition, the machine had to beperiodically shut down and those elements of the optical system whichwere coated with dust had to be handcleanecl to restore the opticalsystem to its clean state.

The manner in which the above and other objects of the invention can beaccomplished will be apparent from the following detailed description ofthe invention.

In the drawings:

FIGURE 1 is a vertical central section of a classifying apparatusincorporating the dust removing apparatus of this invention.

FIGURE 2 is an enlarged section taken along line 22 of FIGURE 1.

Referring now to FIGURE 1 there is shown an article sorting orclassifying machine incorporating the dust removing apparatus of thisinvention. For a detailed description of the construction and operationof the optical system and the main structural components, referenceshould be had to U.S. Patent No. 3,009,571 issued November 21, 1961, andapplication Serial No. 144,601 filed October 12, 1961 entitled ColorSorting with Polarized Light, now abandoned, assigned to the sameassignee as this invention. The classifying apparatus with which thisinvention is associated includes a generally cylindrical housingsupported in an upright position by a base 12. Articles to be classifiedare deposited in a funnel 14 which defines, with a lamp housing 16, anannular discharge passage 18 through which the articles to be classifiedpass. As the articles pass through the annular discharge passage 18 theyfall upon a conical skirt 20 having a radially extending downwardlydirected upper surface terminating at another annular opening 22 that isdefined by the conical skirt 20 and a circumferential partition 24. Uponleaving the annular open- 3,236,376 Patented Feb. 2a, 1966 ing 22, therice is free to fall downwardly toward either of two generally annularchambers 26 and 28. A series of circum'ferentially adjacent air valves30 (only two of which are shown) are located in a plane normal to theaxis of the tubular housing 10 and between the annular discharge 22 andthe annular chambers 26 and 28. As explained in the above mentionedpatent and in the above mentioned copending application, the air valves30 are operative to effect changes in the trajectory of the articles asthey fall from the opening 22 toward the annular chambers 26 and 28 bybeing responsively con nected to the optical system of the apparatus sothat the air valves are selectively opened to direct a jet of airradially inwardly at the appropriate time to thereby divert the rejectedarticles into the annular chamber 28. The portion of the housing 10within which the articles being classified are deflected from theirnormal trajectory will hereinafter be referred to as the inspectionzone. The annular chambers 26 and 28 have a common lower stationaryannular wall 32 which includes openings 34 and 36 through which theclassified articles pass into associated chutes 38 and 4%, which conveythe classified articles to suitable containers positioned to receive thearticles.

A par-t of the optical inspection system associated with the air rejectvalves 3:; is rotatably mounted in a tubular sleeve 42 having lower andupper bearings 44 and 46 respectively which rotatably support a tubularshaft 48. A tubular lens mount 59 is rotatable with and secured to theupper end of the tubular shaft 48 and supports lenses 52, 54, 56, 53 andmirrors 60 and 62. The remaining elements of the optical system aremounted Within the lamp housing 16 and include a lamp 64, which is thesource of illumination, and lenses 66 supported on the upper end of afixed optical tube 68.

The structure described thus far is disclosed in the above-mentionedpatent and application, and the manner in which the articles to beclassified are classified is also explained.

As previously mentioned, due to the sliding friction between thearticles themselves and between the walls of the passageways during theclassifying operation of previous machines, dust was formed anddeposited on the lenses 54 and 56 particularly. The deposited dustreduced the accuracy of the optical system because the amount of lighttransmitted to the inspection zone was greatly reduced, thus reducingthe responsiveness of the associated light-analyzing components. Thisinvention solves this problem by providing streams of flowing fluid,preferably air, directed in a manner to, in part, entrain the dust inthe air streams and to effect a wiping action on the optical elementssubject to be coated with dust. The streams of fluid have the attendantadvantage of dissipating the heat produced by the lamp 64. In achievingsuch a result this invention includes a fan or blower 70, which may takeany conventional form, having the discharge thereof in communicationwith the upper portion of the lamp housing 16 by a conduit 72. Anannular partition 74, supporting and centering the optical tube 68, hasa series of circum ferentially spaced holes 76 formed therein throughwhich the air discharged by the blower 70passes downwardly as shown bythe illustrated arrows. An annular ring '78, having the innercircumferential wall formed to define a converging passageway, isprovided at the lower surface of the lamp housing 16. As willhereinafter be explained, a part of the air in the lamp housing 16 flowsthrough the passageway formed by the annular ring '78. A tubulartransparent light shield 80, having the lower end thereof outwardlyflared, encloses a portion of the lens mount 50 and has the upper endthereof extending into the lamp housing 16.

The light shield has its outer surface spaced radially inwardly from theadjacent margin of the annular ring 78 and its inner surface spacedradially outwardly from the outer surface of the lens mount 50 tothereby define concentric annular openings through which the air fromthe blower 7O passe-s. The air passes through the annular openings andforms fluid streams. As shown, the stream P is adjacent the outersurface of the shield 80 and thes tream Q is between the passagewaydefined by the inner surface of the shield 80 and the exterior of thelens mount 50. The lower flared end of the light shield 80 is supportedon an annular ring 82 which is in turn supported by a tubular sleeve 84having the upper end secured to the ring 82 and the lower end secured tothe tubular sleeve 42. Another tubular ring 86, concentric with andradially spaced from the ring 84, has the lower end thereof secured toaflange 88 to define an annular opening 90 forming the entrance to thepassageway included between the tubular rings 84 and 86. The chamber 28has an outwardly and downwardly directed conical wall 92 having theupper circular margin thereof secured to the upper end of the tubularring 86, as shown in FIG- URE 1. A conical baflle 94 has its lower endsecured to the outer surface of the conical wall 92 and the upper endspaced from the adjacent flared portion of the light shield 80 to definean annular passageway 96 through which the air in stream P flows duringits downward movement toward the passageway included between by thetubular rings 84 and 86. The inner diameter of the tubular ring 82 isgreater than the diameter of the adjacent portion of a lens mount 50 sothat a passageway 98 is formed through which the air from the air streamQ flows into the tubular ring 84 as shown. The tubular ring 84 includesa series of circumferentially spaced holes 100 formed through the wallthereof to permit flow of the fluid into the annular cavity defined bythe tubular members 84 and 86. The upper portion of the tubular sleeve42 includes a radially enlarged flange 102 having a series of axiallyextending circumferentially spaced holes 104 through which all of thefluid flows to an annular plenum chamber 106. A conduit 108 connected tothe plenum chamber and to the inlet of a blower 110 is provided formoving the fluid from the plenum chamber 106.

During operation, the tubular shaft 48 and the lens mount 50 are rotatedin unison by a conventional electric motor 112 which has a toothed belt114, and toothed pulleys 116 and 118 connected to the motor and to theshaft 48 respectively. Another motor 120, by means of a sprocket chain122 and sprockets 124 and 126 connected to the motor shaft and to alower wall 125 of chamber 28 respectively, effects rotation of apartition 128 of the chamber 28. An annular wall 134 coacts with theouter wall of chamber 26 to form an annular trough 135 at the lower endof chamber 26, and wall 134 coacts with a second annular wall 136 todefine a trough 13-7 at the lower end of chamber 28. Brushes 130 and 162are carried by the partition 128 and have their bristles in frictionalsliding engagement with the lower annular plate 32. The brush 130 movesalong trough 135 while brush 132 moves along trough 137 to therebyeffect movement of the classified articles to the openings 34 and 36. Itwill be noted, therefore that during operation of the machine both thelens mount 50, and the partition 128, are being rotated.

In operation, the dust removing apparatus associated with theclassifying machine operates as follows. Both of the blowers 70 and 110move the air in the direction indicated by the arrows. The :airdischarged into the lamp housing 16 is rapidly decelerated since itabruptly passes into a larger flow area. Such deceleration causes rapiddiffusion, and a substantial amount of turbulence is produced which iseffective to increase the amount of heat transferred from the source oflight to the air. The air then passes through the holes '76 and entersthe concentric annular passageways to form streams P and Q.

The area provided by the concentric annular passageways is greatlyreduced compared to the area of the passage in the lamp housing andtherefore rapid acceleration of the air in the passageways is causedand, as a consequence, turbulent flow conditions are againre-established in streams P and Q. This is particularly desirable sinceturbulent flow effects a very vigorous scrubbing action on the interiorand exterior surfaces of the light shield and on the lenses 54 and 56thereby maintaining these parts substantially free of dust. The airflowing downwardly in the outer stream P encounters the outwardly flaredportion of the light shield causing a change in momentum of the fluidand consequently effecting a wiping action on the flared portion. Thisaction of the fluid in the flared portion is particularly significantbecause the light reflected from the articles being classified throughthe lens 54 must pass through the flared portion of the transparentlight shield 80. The air in the stream P continues through thepassageway 96 where it is effective to entrain a high percentage of thedust particles in the chambers 26 and 28. The air continues through theopening 96, through the passageway 90, and into the space bounded by thetubular rings 84 and 86, and, by means of the holes 104, discharges intothe annular plenum 106.

The air in the stream Q continues downwardly through the passageway 98to the interior of the tubular ring 84, through the holes and 104 andthence to the annular plenum 106 carrying with it any dust that may bein its flow path. As shown by the arrows, the flow of air in the plenum106 is introduced by the blower which is connected to the annular plenum106 by the conduit 108. In this manner, substantially all of the dustthat may interfere with the optical system of the classifying apparatusis swept away as it is being formed.

The invention having been thus described, that which is desired to beprotected by Letters Patent is:

1. An apparatus for preventing accumulation of dust on the opticalsystem of an optical classifying apparatus in a machine having wallmeans defining a dust dispersing chamber comprising optical inspectionmeans located within said chamber including a lens, means passing astream of gaseous fluid between said wall means and said lens forentraining the dust in the stream, and means for conveying the dustladen stream away from said lens.

2. An apparatus for preventing accumulation of dust on the opticalsystem of an optical classifying apparatus in a machine having wallmeans defining a dust dispersing chamber comprising optical inspectionmeans located within said chamber including a lens, light transmittingshield means disposed between said chamber and said lens, means passinga stream of gaseous fluid at least around said shield means forentraining the dust in the stream, and means for conveying the dustladen stream away from said lens.

3. An apparatus for preventing accumulation of foreign matter on theoptical system of an optical classifying apparatus comprising opticalinspection means having a rotatable lens mount, a tubular lighttransmitting shield around said lens mount shielding the lens from suchforeign matter, means cooperating with said shield to define concentricpassageways, means for passing foreign matter-entraining fluid throughsaid passageways and over said lens and said shield, 'a plenumcommunicating with said passageways to receive the fluid therefrom, andmeans for exhausting the fluid from said plenum.

4. An apparatus for sorting articles that create dust during passagethrough the apparatus comprising means defining a circular inspectionzone across which the articles pass for inspection and wherein the dustis dispersed by the articles, optical inspection means centrally of saidzone for directing a beam of light in said zone, tubular transparentdust shield means disposed between said inspection zone and said opticalinspection means, and means passing streams of gaseous fluid to theexterior and the interior of said shield means for entraining andremoving the dust created by the articles being sorted.

5. An apparatus for sorting articles that create dust during passagethrough the apparatus comprising means defining a circumferentialinspection zone across which the articles pass for inspection andwherein the dust is dispersed by the articles, a rotatable opticalinspection means centrally of said zone for directing a beam of light insaid zone, transparent dust shield means disposed between saidinspection zone and said optical inspection means, and means pumping airpast the exterior and the interior of said shield means for entrainingand removing the dust created by the articles being sorted.

6. An apparatus for sorting articles that create dust during passagethrough the apparatus comprising means defining a circular inspectionzone across which the articles pass for inspection and wherein the dustis dispersed by the articles, optical inspection means for directing abeam of light in said zone, transparent dust shield means disposedbetween said inspection zone and said optical inspection means, saidshield and said optical inspection means defining annular passagewaysthrough which dustentraining air flows, and air blowers cooperativelyassociated on opposite ends of said passageways to move air through saidpassageways.

7. An apparatus for sorting articles that create dust during passagethrough the apparatus comprising an air blower, a housing having a lamptherein and having the discharge conduit of said blower in communicationtherewith, an elongated rotatable lens mount having one end portionthereof extending into said housing, a transparent tubular shieldsurrounding said lens mount and extending from said one portionlongitudinally along said lens mount, said housing, said lens mount, andsaid shield defining concentric annular fluid passageways through whichthe air from said blower flows, and another blower having the inducerthereof in communication with thedownstream end of said annularpassageways to exhaust the air and the dust entrained thereby from theapparatus.

8. An apparatus for sorting articles that create dust during passagethrough a dust dispersing chamber defined by w-all means comprising anair blower, a housing having a lamp therein and having the dischargeconduit of said blower in communication therewith, an elongatedrotatable lens mount having one end portion thereof extending into saidhousing, a transparent tubular shield within said chamber, surroundingsaid lens mount and extending from said one end longitudinally alongsaid lens mount forming annular fluid passageways, and a second blowerexhausting the air and the dust entrained thereby from the apparatus.

9. An apparatus for sorting articles that disperse dust during passagethrough an inspection zone in the apparatus comprising a blowerconnected to a housing having a lamp therein, said housing having alower annular end wall circumscribing a circular discharge outlet, anelongated lens mount having one end portion extending into said outlet,a transparent tubular shield surrounding said lens mount between theinspection zone and the lens mount and extending into said outlet, saidhousing, lens mount and shield defining concentric annular paths alongwhich the gas from said blower flows, the annular end wall, tu bularshield, and lens mount providing restrictions in said paths to cause thegas to accelerate so as to assist in the entrainment and removal offoreign matter from said paths.

10. An apparatus for sorting articles that create dust during passagethrough an inspection zone therein, comprising a first air blower, ahousing having a lamp therein and having the discharge conduit of saidblower in com munication therewith, an elongated rotatable lens mounthaving one end portion thereof extending into said housing, atransparent tubular shield surrounding said lens mount between saidinspection zone and said lens mount and extending into said housing,said lens mount and said shield forming annular air passageways, asecond air blower communicating with said air passageways, said firstand second air blowers being effective to cause a stream of air to flowthrough said passageways entraining dust therein, and means toaccelerate the flow of air past the lens mount and shield so as toenhance the entrainment of the dust into the air stream.

References Cited by the Examiner UNITED STATES PATENTS 2,269,794- 1/1942 Stechbart.

2,849,915 9/ 8 Kennedy,

2,979,986 4/1961 Miller.

3,097,744 7/ 1963 Hutter et al 209-4 1 1.6

M. HENSON WOOD, JR., Primary Examiner. ROBERT B. REEVES, Examiner.

1. AN APPARATUS FOR PREVENTING ACCUMULATION OF DUST ON THE OPTICALSYSTEM OF AN OPTICAL CLASSIFYING APPARATUS IN A MACHINE HAVING WALLMEANS DEFINING A DUST DISPERSING CHAMBER COMPRISING OPTICAL INSPECTIONMEANS LOCATED WITHIN SAID CHAMBER INCLUDING A LENS, MEANS PASSING ASTREAM OF GASEOUS FLUID BETWEEN SAID WALL MEANS AND SAID LENS FORENTRAINING THE DUST IN THE STREAM, AND MEANS FOR CONVEYING THE DUSTLADEN STREAM AWAY FROM SAID LENS